The present invention relates in general to calorimeters and in particular to a new and useful calorimeter and technique which measures the amount of oxygen utilized in completely catalytically burning combustible products in a test sample, which amount is proportional to the calorific value of the test sample.
Various techniques of calorimetry are known. One such technique known as water-flow calorimetry, relies on the principle of operation wherein heat is transferred by the combustion of a continuous flowing gas to continuously flowing water. The amount of water and the volume of gas combusted are known and the rise of temperature in the water is measured. A disadvantage of this technique is in response time, losses due to heat exchange with surrounding and the difficulty of insuring complete transfer of heat from the combustion products to the water.
Another technique known as differential expansion calorimetry has been utilized by the Sigma Instrument Company Limited and is disclosed in a publication by that company entitled "Mark II Recording Calorimeter for Trouble-Free Recording". In this device the heat capacity of specific gases is obtained by venting the hot combustion products through two concentrically mounted metal tubes. The differential expansion of the tubes has a direct relationship to the thermal input of the gas being burned. The disadvantage of this technique again is heat exchange with the surroundings, particularly where the instrument might be heated unequally.